The sex steroid hormones (estrogen and progesterone) stimulate growth, maturation, and the development of new biochemical capacities in their reproductive organs. In chick oviduct tissue, estrogen and progesterone can stimulate the synthesis of egg white proteins. Substantial evidence has accumulated to support the notion that transcription is the primary site for steroid hormone regulation of gene expression. In order to understand the transcriptional control mechanisms in thi system, it is necessary to develop a cell-free system reconstituted from purified components so that an in vivo event can be duplicated. In this proposal we design experiments to isolate, purify, and study the mechanism of action of transcriptional factors for polymerase II genes. The studies will involve various aspects of biochemistry, molecular biology, and some immunochemistry. It is expected that the results derived from this project will be relevant to the understanding of action of steroid hormones on maternal physiology and fetal development. The following proposal should also be pertinent to development of more precise hypothesis for the mechanism of action of hormones in general, and more specifically, steroid hormones.